Glossary

Ecommerce marketing glossary

The terms that show up in ad accounts, analytics and feed tools, defined in one sentence each and then worked through with real arithmetic.

Metrics with a formula

Add to cart rate: Add to cart rate is the share of visits, or of product page views, in which a shopper puts at least one item into the cart.
Average order value (AOV): Average order value (AOV) is the revenue a store took in a period divided by the number of orders placed in that period.
Blended CAC: Blended CAC is total marketing spend across every channel in a period divided by every new customer acquired in that period, regardless of which channel brought them.
Break-even ROAS: Break-even ROAS is the return on ad spend at which an advertised sale covers its own product cost, fulfilment cost and advertising cost with nothing left over.
CAC payback period: CAC payback period is the time it takes for the contribution margin a customer generates to add up to what the store spent acquiring them.
Cart abandonment rate: Cart abandonment rate is the share of shoppers who added at least one item to a cart and did not place an order in the same period.
Checkout abandonment rate: Checkout abandonment rate is the share of shoppers who opened the checkout and did not complete payment, calculated as one minus orders divided by checkouts started.
Contribution margin: Contribution margin is the money an order leaves behind once every cost that the order itself caused has been paid: the goods, the packaging, the carrier charge the store absorbs, the payment fee and a share of expected returns.
Customer acquisition cost (CAC): Customer acquisition cost (CAC) is the total spent on marketing and sales to win new customers in a period, divided by the number of new customers won in that period.
Customer lifetime value (LTV): Customer lifetime value (LTV) is the total profit a customer produces for a store over a stated horizon, counting every order they place and subtracting the variable cost of fulfilling each one.
Ecommerce conversion rate: Ecommerce conversion rate is the share of visits that end in a purchase, calculated as orders divided by sessions for a period and expressed as a percentage.
Impression share: Impression share is the number of impressions an ad actually received divided by the number it was eligible to receive, expressed as a percentage.
Incrementality: Incrementality is the portion of sales that happened only because an ad ran, rather than sales the store would have received anyway.
Marketing efficiency ratio (MER): Marketing efficiency ratio (MER) is total store revenue for a period divided by total marketing spend for the same period, across every channel at once.
Profit on ad spend (POAS): Profit on ad spend (POAS) is the gross profit generated by advertised orders divided by the ad spend that produced them.
Repeat purchase rate: Repeat purchase rate is the share of a store's customers who have placed more than one order, measured over a stated window.
Return on ad spend (ROAS): Return on ad spend (ROAS) is the revenue an ad platform attributes to a campaign, ad group or account, divided by the amount spent on it over the same window.
Revenue per session: Revenue per session is the revenue a store earned divided by the number of sessions that produced it, usually reported for a channel, a device, a landing page or a campaign.
Subscription churn rate: Subscription churn rate is the share of active subscribers a store loses in a period, calculated as subscribers cancelled or lapsed divided by those active at the start.

Concepts and attributes

Attribution window: An attribution window is the period after an ad interaction during which a later purchase is still credited to that interaction.
Canonical tag: A canonical tag is a link element carrying the attribute rel set to canonical, placed in the head of a page, that names the URL a store considers the preferred version of that content.
Consent Mode: Consent Mode is Google's mechanism for telling its tags whether a visitor has agreed to storage and to the use of their data for advertising, so the tags can change their behaviour accordingly.
Core Web Vitals: Core Web Vitals are the three metrics Google uses to describe how a page feels to the people who load it: Largest Contentful Paint for loading, Interaction to Next Paint for responsiveness, and Cumulative Layout Shift for visual stability.
Crawl budget: Crawl budget is the number of URLs a search engine is willing and able to fetch from a site in a given period.
Custom labels: Custom labels are five optional product feed attributes, numbered custom_label_0 through custom_label_4, that a store fills with values of its own choosing so campaigns can be subdivided by something Google does not know.
Data layer: Data layer is the structured JavaScript object, on most stores the window.dataLayer array that Google Tag Manager reads, into which the storefront pushes page details and ecommerce events such as view_item, add_to_cart, begin_checkout and purchase, each carrying an items array.
Enhanced conversions: Enhanced conversions is a Google Ads feature in which the customer details already collected at checkout, such as email address, phone number and billing name and address, are hashed in the browser and sent alongside the conversion so Google can match the order to an ad interaction it would otherwise have missed.
Faceted navigation: Faceted navigation is the set of filters and sort controls a store puts on its category pages so shoppers can narrow a range by size, colour, price, brand, rating or availability.
Google product category: Google product category is the feed attribute that places a product inside Google's own published taxonomy, submitted either as the full category path or as the numeric identifier for that path.
GTIN: GTIN (Global Trade Item Number) is the globally unique number encoded in a product's barcode, licensed through GS1 to the brand owner, in one of four lengths: GTIN-8, GTIN-12 (the UPC used in North America), GTIN-13 (the EAN used elsewhere, and the form ISBNs take for books) and GTIN-14 for case packs.
Hreflang: Hreflang is an annotation that tells search engines which language and, optionally, which country a page is meant for, so the right version of the same content is shown to the right audience.
Index bloat: Index bloat is the condition of having far more URLs in a search engine's index than a store has pages worth showing to anyone.
Interaction to next paint (INP): Interaction to next paint (INP) measures the delay between a visitor interacting with a page and the browser painting the visual response, reported for a whole visit rather than for a single click.
Item group id: Item group ID is the product feed attribute that tells Merchant Center which rows are variants of the same product.
MPN: MPN (manufacturer part number) is the alphanumeric code a manufacturer assigns to one specific product, submitted to Merchant Center in the mpn attribute alongside brand so that Google can identify the item when no GTIN exists.
Product structured data: Product structured data is a machine readable description of what a product page is selling, written in the schema.org vocabulary and usually placed on the page as a script element of type application/ld+json.
Product type attribute: The product type attribute is the feed field where a store sends its own classification of a product, written as a path in its own words rather than chosen from Google's list.
Server-side tagging: Server-side tagging is a tracking setup in which the browser sends each event to a tagging server the store controls, usually a Google Tag Manager server container on a subdomain such as gtm.yourstore.com, and that server forwards the data on to GA4, Google Ads, Meta and any other destination.
Supplemental feed: A supplemental feed is a secondary data source in Merchant Center that adds attributes to, or overrides attributes on, products that already exist in a primary feed.
Target ROAS bidding: Target ROAS bidding is an automated strategy in which you tell Google Ads the return you want from a campaign and the system sets each bid to pursue it, raising bids in auctions where it predicts high conversion value and lowering them where it predicts little.

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